Aurin
Skeletal formula of aurin
Ball-and-stick model
Names
Preferred IUPAC name
4-[Bis(4-hydroxyphenyl)methylidene]cyclohexa-2,5-dien-1-one
Other names
Aurin, corallin, p-rosolic acid, C.I. 43800
Identifiers
3D model (JSmol)
2055205
ChEMBL
ChemSpider
ECHA InfoCard 100.009.129
EC Number
  • 210-041-8
UNII
  • InChI=1S/C19H14O3/c20-16-7-1-13(2-8-16)19(14-3-9-17(21)10-4-14)15-5-11-18(22)12-6-15/h1-12,20-21H checkY
    Key: FYEHYMARPSSOBO-UHFFFAOYSA-N checkY
  • InChI=1/C19H14O3/c20-16-7-1-13(2-8-16)19(14-3-9-17(21)10-4-14)15-5-11-18(22)12-6-15/h1-12,20-21H
    Key: FYEHYMARPSSOBO-UHFFFAOYAG
  • C1=CC(=O)C=CC1=C(C2=CC=C(C=C2)O)C3=CC=C(C=C3)O
Properties
C19H14O3
Molar mass 290.318 g·mol−1
Appearance see text
Density 1.283 g/cm3
Melting point 308 °C (586 °F; 581 K) (decomposes)
Insoluble
UV-vis (λmax) 482 nm[1]
-161.4·10−6 cm3/mol
Hazards
GHS labelling:
GHS07: Exclamation mark[1]
Danger
H315, H319, H335[1]
P261, P305+P351+P338[1]
NFPA 704 (fire diamond)
NFPA 704 four-colored diamond
1
1
0
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)
Infobox references

Aurin (C.I. 43800), sometimes named rosolic acid or corallin is an organic compound, forming yellowish or deep-red crystals with greenish metallic luster. It is practically insoluble in water, freely soluble in alcohol. It is soluble in strong acids to form yellow solution, or in aqueous alkalis to form carmine red solutions.

Aurin (pH indicator)
below pH 5.0 above pH 6.8
5.0 ⇌ 6.8

Due to this behaviour it can be used as pH indicator with pH transition range 5.0 - 6.8. It is used as an intermediate in manufacturing of dyes.

Synthesis

Aurin was first prepared in 1834 by the German chemist Friedlieb Ferdinand Runge, who obtained it by distilling coal tar. He named it Rosölsäure or Rosaölsäure (red oil acid).[2][3] In 1861, the German chemists Hermann Kolbe and Rudolf Schmitt presented the synthesis of aurin by heating oxalic acid and creosote (which contains phenol) in the presence of concentrated sulfuric acid.[4] (Gradually, chemists realized that commercial aurin was not a pure compound, but was actually a mixture of similar compounds.[5][6])

Aurin is formed by heating of phenol and oxalic acid in concentrated sulfuric acid.

Safety

Aurin may cause eye, skin, and respiratory tract irritation. Ingestion and inhalation should be avoided.

Aurin was reported to have endocrine disruptor chemical (EDC) properties.[7]: 149 

References

  1. 1 2 3 4 Sigma-Aldrich Co., p-Rosolic acid. Retrieved on 2014-05-06.
  2. ↑ Runge, F. F. (1834). "Ueber einige Produkte der Steinkohlendestillation" [On some products of coal tar distillation]. Annalen der Physik und Chemie (in German). 31: 65–78. ; see p. 70.
  3. ↑ In 1859, the German-English chemist Hugo Müller (de) (1833–1915) found that rosolic acid could be produced simply by mixing phenol and calcium carbonate and then exposing the mixture to air for a prolonged time. Müller, Hugo (1859). "Note on rosolic acid". Quarterly Journal of the Chemical Society. 11 (1): 1–5. doi:10.1039/QJ8591100001.
  4. ↑ Kolbe, H.; Schmitt, R. (1861). "Rother Farbstoff aus dem Kreosot" [Red dye from creosote]. Annalen der Chemie (in German). 119: 169–172.
  5. ↑ See the papers of the English chemist Richard S. Dale and the German-English chemist Carl Schorlemmer and of the German chemist Heinrich Fresenius (de) (1847–1920).
  6. ↑ Thorpe, Thomas Edward, ed., A Dictionary of Applied Chemistry, 2nd ed. (London, England: Longmans, Green, and Co., 1913), vol. 5, "Triphenylmethane colouring matters," p. 551. From p. 551: "The researches of Dale and Schorlemmer, Zulkowski, and others have shown that common aurin consists of a mixture of a number of substances, which, in a pure state, are well crystallised."
  7. ↑ Blair, R. M. (1 March 2000). "The Estrogen Receptor Relative Binding Affinities of 188 Natural and Xenochemicals: Structural Diversity of Ligands". Toxicological Sciences. 54 (1): 138–153. doi:10.1093/toxsci/54.1.138. ISSN 1096-0929. PMID 10746941.
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